Method of forming hollow forged valves



Feb. 26, 1935. w. SCRIMGEOUR IETHOD OF FORMING HOLLOW FORGED VALVES Filed Dec. 6, 1935 22 /////l/////////// ur//A Patented F eb. 26, 1935 UNITED STATES PATENT OFFICE William Scrimgeour, Washington, D. 0. Application December 6, 1933, Serial No. 701,210

6 Claims. (01. 229-1563) 1 particularly applicable to the manufacture of valves of relatively large size, such as employed in large Diesel engines, and the present invention is especially useful in the manufacture of smaller valves such as may be used in automobile engmes.

Objects of the invention are to provide im-,

proved methods of forming hollow one-piece valves by forging operations and to provide improved valves made by such forging processes. An object is to provide methods of forming hollow valves by forging steps which include the upsettingof the closed end of a hollow blank and the working down of the remainder of the blank to form a stem integral with the head.

These and other objects and advantages of the invention will be apparent from the following specification when taken with the accompanying drawing, in which:

Fig. 1 is an elevation of a cylindrical blank,

Figs. 2 to 6, inclusive, are longitudinal central sections illustrating successive steps in the formation of a valve from the cylindrical blank of Fig. 1,

Fig. 7 is a side elevation of a valve at the close of the forging operations, I

Fig. 8 is ,a central section through a die and blank, illustrating the transformation of the blank from the Fig. 2 to the Fig. 3 form,

Fig. 9 is a transverse section through swaging dies such as used in transforming the blank into the Figs. 4 and 5 forms,

Figs. 10 and 11 are central sections illustrating the upsetting of the end of the blank to form the valve head/and Fig. 12 is a central section through a modified valve having a hollow head but a closed stem.

In the drawing, which illustrates the preferred method of forming a hollow valve, the starting blank 1 is a steel cylinder having a diameter substantially less than that of the finished valve head and substantially greater than that of the finished stem, the length of the blank being materially shorter than that of the finished valve. The blank is counterbored, as indicated at 2, to leave a closed end or wall 3 which is much thicker than the desired wall thickness of the valve head. The

next step is the transformation of the blank into the form illustrated in Fig. 3 by punching the heated closed end of, the blank in dies 4, 4 to round off the closed, end by displacing the excess end wall material of the blank rearwardly along the punch 5. The dies 4,4 are preferably countersunk to form a small central lug 6 at the extreme end of the blank, this lug providing material which may be slotted to provide a kerf for receiving the end of a screw driver or other valvegrinding tool.

The punching of the heated blank to impart a rounded contour to the closed end is entirely practical as the slightly tapered punch 5 is quickly withdrawn from the heated end of the blank before it can expand and become locked to the blank.

Attention is directed to the fact that the punching or die-shaping of the end of the blank preferably leaves the thickness of the rounded end wall, i. e., the section A of the blank, somewhat less than that of the cylindricalwall of the hollow blank.

The portion B of the blank, Fig. 3, immediately back of the rounded end is then heated and forged in swaging dies, such as the dies 8 of Fig. 9, to form an approximately spherical ball at the end of the blank by reducing the section adjacent the ball end to the approximate diameter of the finished valve, Fig. 4. During this forging operation, the wall thickness at the rear of the ball end will be reduced somewhat as the metal is displaced inwardly and rearwardly by the repeated blows of the swaging dies.

The remaining or large diameter portion of the blank is then heated and worked down, for example in another set'of swaging dies or hammers, to form an elongated, hollow stem, as shown in Fig. 5 At intervals during, or at the close of this operation, the bore of the stem may be reamed.

The ball head is then heated and upset or shaped to its final form, Figs. 6 and '7, by placing the blank in the longitudinally split die members 9, 9 and forcing the movable die 10 against the ball end. The dies are so shaped that this operation imparts the final form to the forged blank. The metal of the heated ball end is readily and substantially uniformly displaced axially and laterally to form a symmetrical hollow head of .uniform wall thickness at the end of the hollow em.

The blank may then be machined, in the usual manner, to form a seat-engaging surface 11 and to cut a kerf 12 in the projection 6. Appropriate grooves may be cut in the end of the stem or it may be otherwise finished to receive a collar or spring seat and a bearing block for engagement by the valve tappet. If desired, the hollow valve may be partially filled in known manner with a heat-exchanging material for facilitating the cooling of the valve. The final forging operations maybe varied somewhat, in accordance with the desired final form of the valve, as they may be so conducted as to leave the forged blank in the most convenient shape for the machining operations.

As shown in Fig. 12, the working down of the stem portion of the blank may be so performed, if desired, that the bore is completely closed to leave a hollow head 13 at the end of a substantially solid stem 14.

While I have described the method which I believe to be preferable, it will be apparent that there is some latitude in the several operations. For example, for valves of some sizes and when employing some materials, it may be convenient and economical to cast a blank in the form shown in Fig. 2. It is also possible to machine a blank to the form shown in Fig. 3, but, in general, the described punching or die-shaping operation for obtaining a blank of this form will be more economical than amachining operation. The

process may be applied to the formation of poppet valves which diii'er in design from the form illustrated and materials other than steel may be employed in forming one-piece hollow valves. It is therefore to be understood that various changes may be made in the series of operations and in the form of the valves without departing from the scope of my invention as set forth in the following claims.

I claim: a

1. The methodof making a poppet valve which comprises forming a closed rounded head on a tubular blank having a. diameter intermediate that of the desired head and stem diameters, reducing the diameter the blank adjacent said rounded end to form a g bbular end on said blank,

"working down the tubular portion of the blank to form an elongated stem, and pressing the globular end to rough-finish the same to the form of the desired hollow head:

2. The method of forming a poppet valve of the hollow head type from atubular blank having one closed end, which method comprises forming a tubular blank with one closed end, working the closed end to substantially hemispherical form, working down the tubular blank adjacent said closed end to form a globular hollow head, working down the remaining tubular portion to form an elongated stem, and compressing the said globular head axially of the stem to form a rela-' tively flat hollow head of relatively large size.

3. The method as claimed in claim 2, in combination with the step of reaming out the elongated stem to provide a bore communicating with the hollow head.

4. The method of forming a poppet valve which comprises forming a tubular blank with a relatively thick wall at one end thereof, pressing the end wall axially to shape the closed end of the blank to a rounded form of substantially the thickness of the desired valve head, working down the adjacent tubular portion of the blank to leave a substantially globular head at the closed end of the blank, working down the remaining tubular portion of the blank to the desired stem that of the finished valve head, the steps whichcomprise forming on the end of said blank 2. substantially globular head of a diameter substantially equal to that of the blank, and compressing said globular head to form a flattened head of enlarged diameter.

WILLIAM SCRIMGEOUR. 

